According to phenomena like reflection,refraction,interference, light is wave nature.but according to phenomena like black body radiation, Photoelectric effect ,light radiation is particles nature. so,light exhibits both characters i.e. wave nature and particle nature.

This two nature is first analysed by de-broglie and gave a hypothesis. This hypothesis is called de-broglie hypotgesis.

According to de-broglie’s, the wavelength of matter(particles) is moving in a space is equal to the ratio of value of planck’s constant and linear momentum of the matter.

so, **λ = h/p**

or,

,where h= planck’s constant

m = mass of matter

v = velocity of matter

**Derivation of de-Broglie’s Hypothesis**

Let us consider a photon of frequency of moving with speed ‘c’and its energy is

**E = hf …….1**)

According to **Einestein mass energy** equivalent to matter is,

**E = mc2 …….2)**

From equation 1 and 2,

**hf = mc2**

**hf/λ = mc. c**

**hc/λ = p.c **

**h/λ = p **

* λ = h/mv [*where p = mv]

It is the required expression of **de-broglie hypothesis. **